An empirical formula, based on power functions, has been found which accurately describes the growth (and decline?) of small mammal populations. We hope to experimentally quantify the demographic, social-behavioral, reproductive, endocrine-physiologic and pathologic parameters influencing the dynamics of the white-footed mouse (Peromyscus leucopus) in freely growing confined population pens. These parameters will be analyzed in a computer based discrete systems model designed for both confined and wild small mammal populations. The model will be used to test the sensitivity and relationships of the parameters to indicate further experimental work as well as to understand how and why the power functions are generated for natality and mortality, hence for population growth.